One of the best open source places to watch a story unfold such as the Bhutto Assassination is on Wikipedia. Authors from all over the world rapidly converge on the site to update it with current news and speculation. As with any source, it is not definitive but it can be up to date and often includes views from all over the world. Currently the site contains a useful list of international reactions and some information regarding the immediate reaction in Pakistan itself. There is also a fairly exhaustive reference list. Expect this site to be updated regularly (a number of references were added while I type this).